Systems and methods for combining signals from multiple active wireless receivers

ABSTRACT

Systems and methods for combining signals from multiple active wireless receivers are discussed herein. An exemplary system comprises a first downconverter, a phase comparator, a phase adjuster, and a second downconverter. The first downconverter may be configured to downconvert a received signal from a first antenna to an intermediate frequency to create an intermediate frequency signal. The phase comparator may be configured to mix the received signal and a downconverted signal to create a mixed signal, compare a phase of the mixed signal to a predetermined phase, and generate a phase control signal based on the comparison, the downconverted signal being associated with the received signal from the first antenna. The phase adjuster may be configured to alter the phase of the intermediate frequency signal based on the phase control signal. The second downconverter may be configured to downconvert the phase-shifted intermediate frequency signal to create an output signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims benefit of U.S. Provisional PatentApplication No. 61/388,483 filed Sep. 30, 2010, and entitled “HighDynamic Receiver and its Applications for Space Diversity” which isincorporated by reference herein.

BACKGROUND

1. Field of the Invention(s)

The present invention(s) generally relate to wireless receivers. Moreparticularly, the invention(s) relate to systems and methods forcombining signals from multiple active wireless receivers.

2. Description of Related Art

In microwave radio systems, receiver protection (backup) systems arecommon. In a typical receiver protection system, there is one mainactive receiver and one or more other secondary “backup” receivers. Thesecondary protection receivers are not actively receiving while the mainactive receiver receives signals from a wireless source (e.g., a toweror other wireless signal transmitting device). If the main activereceiver fails or is operating below an acceptable limit, the mainactive receiver may be switched such that the main active receiver is nolonger actively receiving and one of the secondary standby protectionreceivers become the main receiver. In the prior art, there is only onereceiver actively receiving at any one time.

Space diversity configuration has not been changed in decades. FIG. 1and FIG. 2 depict today's two most commonly used 1+1 configurations inthe prior art. FIG. 1 depicts a main active receiving radio frequencyunit (RFU) 102 and a secondary protection RFU 102 in the prior art. InFIG. 1, a main active receiving unit 102 in an environment 100 receivesa wireless signal from a wireless communication tower 106 (e.g., celltower or other microwave radio device) via an antenna. If the mainactive receiving unit 102 fails or falls below an acceptable level ofperformance, the main active receiving unit 102 may go into standby modeand the secondary protection receiving unit 104 may begin to activelyreceive, thereby receiving the signal from the wireless communicationtower 106.

FIG. 2 depicts a main active receiving radio frequency unit (RFU) 202and a secondary protection RFU 204 when an RFU enclosure is optimizedfor protection in the prior art. In an environment 200, a main activereceiving unit 202 and a secondary protection receiving unit 204 receivethe signal from one antenna (i.e., wireless communication tower 206).For example, an antenna receives a wireless signal from the wirelesscommunication tower 106 and provides the signal to a filter and/ordiplexer. The filter and/or diplexer provide the signal to the mainactive receiving radio frequency unit 202. A coupler provides the signalto the secondary protection receiving radio frequency unit 204 as well,however, like the protection receiving unit in FIG. 1, the secondaryprotection receiving radio frequency unit 204 is typically not activelyreceiving. If the main active receiving unit 202 fails or falls below anacceptable level of performance, the main active receiving unit 202 maygo into standby mode (i.e., the main active receiving unit 202 may stopactively receiving) and the secondary protection receiving unit 204 mayactively receive. As a result, the secondary protection receiving unit204 may receive the signal from the wireless communication tower 106.

In both configurations of FIGS. 1 and 2, two receivers are on all thetime, however, the systems may decide to use either the main activereceiving unit or the secondary protection receiving unit. Thedetermination to switch to a receiving radio frequency unit may be basedon a quality alarm of each channel such as slope alarm, equalizationalarm, or RSL (receiver signal level) low alarm. In legacyimplementations, this decision may occur in real time either on abit-by-bit or data block by data block basis.

Unfortunately, when the system switches receivers, performance suffers(e.g., the system may no longer be hitless). Today's 1+1 architectureonly achieves hitless switching protection during multi-path fadingconditions. Further, other failure mechanisms, including equipmentfailure, generally affect the performance (e.g. the system is nothitless).”

SUMMARY OF THE INVENTION

Systems and methods for combining signals from multiple active wirelessreceivers are discussed herein. An exemplary system comprises a firstdownconverter, a phase comparator, a phase adjuster, and a seconddownconverter. The first downconverter may be configured to downconverta received signal from a first antenna to an intermediate frequency tocreate an intermediate frequency signal. The phase comparator may beconfigured to mix the received signal and a downconverted signal tocreate a mixed signal, compare a phase of the mixed signal to apredetermined phase, and generate a phase control signal based on thecomparison, the downconverted signal being associated with the receivedsignal from the first antenna. The phase adjuster may be configured toalter the phase of the intermediate frequency signal based on the phasecontrol signal. The second downconverter may be configured todownconvert the phase-shifted intermediate frequency signal to create anoutput signal.

The downconverted signal may comprise the intermediate frequency signal.The received signal may be received from a diplexer which is coupled tothe first antenna. Further, the received signal may be filtered with alow noise amplifier after being provided from the diplexer.

In some embodiments, the first downconverter is configured to mix afiltered oscillator signal with the received signal to create theintermediate frequency signal. The system may further comprisecomprising comparing a gain to a predetermined gain value and adjustingthe gain of the downconverted phase-shifted intermediate frequencysignal based on the comparison.

In various embodiments, the system of claim 1, further comprises asecond radio frequency unit configured to receive the received signalfrom a second antenna, the second radio frequency unit configured toalter a phase of the received signal from the second antenna to a phasethat is substantially similar to the altered phase of the intermediatefrequency signal of the first radio frequency unit. The second radiofrequency unit may be configured to adjust a gain of an output signal,the gain of the output signal of the second radio frequency unit beingsubstantially similar to the gain of the output signal of the firstradio frequency unit. The system may further comprise a signal combinerconfigured to combine the output signal from the first radio frequencyunit and the output signal from the second radio frequency unit.Moreover, the system may further comprise a postdistortion moduleconfigured to add distortion to the output signal and a demodulatorconfigured to receive the output signal from the postdistortion moduleand provide in-phase (I) and quadrature (Q) signals.

The system may also further comprise a waveguide configured to receivethe received signal from the first antenna and provide the receivedsignal to the first downconverter. In various embodiments, the firstantenna is part of a point-to-point microwave communication system.

An exemplary system may comprise a first receiving radio frequency unit,a second receiving radio frequency unit, and a signal combiner. Thefirst receiving radio frequency unit may be configured to compare aphase of a received signal from a first antenna to a predetermined phasevalue, and to adjust the phase of the received signal from the firstantenna to generate a first phase-adjusted signal. The second receivingradio frequency unit may be configured to compare a phase of a receivedsignal from a second antenna to the predetermined phase value, and toadjust the phase of the received signal from the second antenna togenerate a second phase-adjusted signal. The signal combiner may beconfigured to combine the first and second phase-adjusted signals, thephase of the first and second phase-adjusted signals being substantiallysimilar.

An exemplary method comprises comparing, by a first receiving radiofrequency unit, a phase of a received signal from a first antenna to apredetermined phase value, adjusting, by the first receiving radiofrequency unit, the phase of the received signal from the first antennato generate a first phase-adjusted signal, comparing, by a secondreceiving radio frequency unit, a phase of a received signal from asecond antenna to the predetermined phase value, adjusting, by thesecond receiving radio frequency unit the phase of the received signalfrom the second antenna to generate a second phase-adjusted signal, andcombining the first and second phase-adjusted signals, the phase of thefirst and second phase-adjusted signals being substantially similar.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a main active receiving radio frequency unit (RFU) and asecondary protection RFU in the prior art.

FIG. 2 depicts a main active receiving radio frequency unit (RFU) and asecondary protection RFU when an RFU enclosure is optimized forprotection in the prior art.

FIG. 3 is a block diagram of exemplary receiving radio frequency unitsand configured to both actively receive a signal from a wirelesscommunication source (e.g., a cell tower) in some embodiments.

FIG. 4 is a block diagram of an exemplary receiving radio frequency unitin some embodiments.

FIG. 5 depicts a circuit diagram illustrating an exemplary receivingradio frequency unit with a phase control module coupled to a couplernear the diplexer and a first downconverter module in some embodiments.

FIG. 6 depicts a circuit diagram illustrating an exemplary receivingradio frequency unit with a phase control module coupled to a firstdownconverter module and a second downconverter module in someembodiments.

FIG. 7 is a flow chart of an exemplary method for combining signals,with similar gain and phase, from different exemplary microwavereceiving radio frequency units.

FIG. 8 is a block diagram of a phase control module in some embodiments.

FIG. 9 is a flow chart of an exemplary method for controlling a phase ofa signal in an exemplary microwave receiving radio frequency unit.

FIG. 10 is an exemplary receiving radio frequency unit with ademodulator and an AGC module in some embodiments.

FIG. 11 is another exemplary receiving radio frequency unit with ademodulator and a postdistortion module in some embodiments.

FIG. 12 is further exemplary receiving radio frequency unit with ademodulator and a postdistortion module in some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

In today's spatial diversity configuration, signal combining techniquesare not used because of the unknown characteristics of each receiver. Invarious embodiments, a signal combining technique for radio receivers isdiscussed. As a result, instead of allowing one receiver to remain in astandby mode, two or more active receivers may be configured to receivesignals, and to adjust the phase and gain of each signal to match theother (thereby overcoming unknown characteristics of each receiver). Thesignals from the two receivers may then be combined.

Since multiple receivers are used with a signal combining technique,information may be retrieved from a wireless signal with increasedaccuracy and greater dynamic range. Further, equipment and power areessentially inoperative “standby mode.” Moreover, in at least some ofthe embodiments discussed herein, hitless protection may be achieved.For example, if one of the receivers fails, the other receiver maycontinue to act as an active receiver without a lapse in performance. Asa result, time is not lost switching from a failed receiver to a standbyreceiver.

FIG. 3 is a block diagram 300 of exemplary receiving radio frequencyunits 302 and 304 configured to both actively receive a signal from awireless communication source 306 (e.g., a cell tower) in someembodiments. In various embodiments, the receiving radio frequency units302 and 304 are part of a microwave communication system.

Both the receiving radio frequency units 302 and 304 may be active(i.e., there is no receiving unit that is in standby mode). In oneexample, both the receiving radio frequency units 302 and 304 receivethe same signal from the wireless communication source 306, process thesignal independently of each other, and then provide the signals to acombiner 308. The combiner 308 combines the signals from the receivingradio frequency units to provide single signal with greater accuracy andincreased dynamic range for potentially further processing and/orcommunication. The combiner 308 may be a signal combiner.

The signal received by both the receiving radio frequency units 302 and304 may contain the same information. In some embodiments, the signalsare part of a single transmission from the wireless communication source(e.g., a broadcast). In various embodiments, the signals are provided ina point-to-point system whereby the wireless communication source 306directly provides the signal to the receiving radio frequency unit 302and the receiving radio frequency unit 304.

Each receiving radio frequency unit 302 and 304 may adjust the phase andgain of the received signal to a predetermined phase and gain,respectively. As a result, the phase and gain of the signal providedfrom the receiving radio frequency unit 302 may be the same phase andgain as the signal provided from the receiving radio frequency unit 304.Subsequently, the combiner 308 may combine the signals from thereceiving radio frequency units 302 and 304 thereby strengthening thesignal.

Each receiving radio frequency unit 302 or 304 may be a part of amicrowave communication system whereby each of the receiving radiofrequency unit 302 and 304 comprise a waveguide, waveguide filter, anddiplexer. In some embodiments, each receiving radio frequency unit 302and 304 receive the signal from the wireless communication source 306,propagate the electromagnetic wave energy through a waveguide, and/orfilter the electromagnetic wave energy with a waveguide filter prior topassing the signal through the diplexer.

Although FIG. 3 depicts two receiving radio frequency units, on wirelesscommunication source, and one combiner, those skilled in the art willappreciate that there may be any number of receiving radio frequencyunits, antennas, diplexers, wireless communication sources and/orcombiners.

FIG. 4 is a block diagram 400 of an exemplary receiving radio frequencyunit 402 in some embodiments. In one example, the receiving radiofrequency unit 402 may be either the receiving radio frequency unit 302or the receiving radio frequency unit 304 described in FIG. 3.

Block diagram 400 comprises an antenna 404 and a diplexer 410 coupled tothe waveguide 406. The waveguide 406 may provide the signal from theantenna 404 to the diplexer 410 via a waveguide filter 408. The diplexer410 may provide the signal to the receiving radio frequency unit 402. Insome embodiments, the receiving radio frequency unit 402 may comprisethe waveguide 406, the waveguide filter 408, and/or the diplexer 410.

The waveguide 406 may be any waveguide kind or type of waveguide. Forexample, the waveguide 406 may be hollow or dielectric. In someembodiments, the waveguide 406 comprises a rectangular to circularwaveguide. The waveguide filter 408 may be any filter coupled to thewaveguide 406 and configured to filter the electromagnetic waves fromthe waveguide 406 (e.g., remove noise).

In various embodiments, the receiving radio frequency unit 402 isconfigured to receive a signal from the antenna 404 via the diplexer 406and adjust the phase of the received signal. The phase of the receivedsignal may be adjusted based on a comparison of the phase of the signaland a predetermined phase value. In some embodiments, the receivingradio frequency unit 402 may also be configured to adjust the gain ofthe received signal. In one example, the receiving radio frequency unit402 may adjust the gain of the received signal based on a comparison ofa gain of the received signal with a predetermined gain value.

The receiving radio frequency unit 402 may be any receiver including,but not limited to, a traditional heterodyne receiver with RXintermediate frequency (IF) output. Those skilled in the art willappreciate that multiple receiving radio frequency units may be used toreceive the same signal (e.g., signals containing the same informationprovided by a wireless communication source). Each receiving radiofrequency unit may adjust the phase of the received signal,respectively, based on the same predetermined phase value. Similarly,each receiving radio frequency unit may adjust the gain of the receivedsignal, respectively, based on the same gain value. As a result, thephase and gain of the signal from each receiving radio frequency unitmay be the same or substantially similar (e.g., the phase and gain ofthe signals may be identical). The signals may be subsequently combinedto strengthen the signal, increase dynamic range, and/or more accuratelyreproduce the information that was wirelessly transmitted.

The receiving radio frequency unit 402 may compriseamplification/attenuation modules 412, 424, and 438, filter modules 416,420, 430, and 434, mixer modules 418 and 432, oscillator modules 418 and432, phase control module 414, automatic gain control modules 426, 440,and 442, and variable phase module 428.

The amplification/attenuation modules 412, 424, and 438 may comprise anamplifier and/or an attenuator configured to amplify and/or attenuate asignal. The amplification/attenuator modules 412, 424, and 438 may beany kind of amplifiers and/or attenuators. Further, theamplification/attenuator modules 412, 424, and 438 may each compriseamplifiers and/or attenuators with any kind of electrical properties.

In some embodiments, the amplifier/attenuator module 412 receives asignal via the antenna 404 and the diplexer 406. Theamplifier/attenuator module 108 may be a low noise amplifier configuredto amplify the signal (or components of the signal) before providing thesignal to the filter module 416 and the phase control module 414.Further, the amplifier/attenuator module 424 may attenuate the signal(or components of the signal) after the signal has been downconverted bythe mixer module 418, the filter module 420, and the oscillator module422. The amplifier/attenuator module 424 may then provide the signal tothe automatic gain control 426. The amplification/attenuator module 438may attenuate the signal (or components of the signal) after the signalhas been downconverted by the mixer 432, the filter module 434, and theoscillator module 436. The amplifier/attenuator module 438 may thenprovide the signal to the automatic gain control 440.

Those skilled in the art will appreciate that each of theamplifier/attenuator modules 412, 424, and 438 may be the same as one ormore other amplifier/attenuator modules. For example,amplifier/attenuator modules 412 and 424 may both be amplifiers sharingthe same electrical properties while amplifier/attenuator module 438 maybe an attenuator. In another example, amplifier/attenuator modules 412and 424 may both be amplifiers but have different electrical properties.

Each amplifier/attenuator module 412, 424, and 438 may include one ormore components. For example, the amplifier/attenuator module 412 maycomprise one or more amplifiers and/or attenuators.

The filter modules 416, 420, 430, and 434 may comprise filtersconfigured to filter the signal. The filter modules 416, 420, 430, and434 may comprise many different types of filters (e.g., bandpass filter,low pass filter, high pass filter, or the like) with many differentelectrical properties. In one example, the filter module 416 may be aband pass filter configured to filter the signal (or components of thesignal) received from the amplification/attenuation module 412 beforeproviding the signal to the mixer module 418. Similarly, filter modules420, 430, and 434 may filter signals (or components of the signals) fromthe oscillator module 422, the phase adjuster 428, and the oscillatormodule 436, respectively.

Those skilled in the art will appreciate that each of the filter modules416, 420, 430, and 434 may be the same as one or more other filtermodules. For example, filters module 416 and 420 may both be filterssharing the same electrical properties while filter module 430 may beanother kind of filter. In another example, filters module 416 and 420may both be filters of a similar type but have different electricalproperties.

Each filter modules 416, 420, 430, and 434 may include one or morecomponents. For example, the filter modules 416 may comprise one or morefilters.

The mixer modules 418 and 432 may comprise mixers configured to mix thesignal received from the antenna with one or more other signals. Themixer modules 418 and 432 may comprise many different types of mixerswith many different electrical properties. In one example, the mixer 418mixes a signal received from the filter module 416 with the filteredoscillating signal from the filter module 420 and the oscillator module422. In another example, the mixer module 432 mixes a signal receivedfrom the filter module 430 with the filtered oscillating signal from thefilter module 434 and the oscillator module 436.

Those skilled in the art will appreciate that each of the mixer modules418 and 432 may be the same as one or more other mixer modules. Forexample, mixer modules 418 and 432 may both be mixers sharing the sameelectrical properties or, alternately, the mixer modules 418 and 432 maybe another kind of mixer and/or with different electrical properties.

Each mixer modules 418 and 432 may include one or more components. Forexample, the mixer module 418 may comprise one or more mixers.

The oscillator modules 422 and 436 may comprise oscillators configuredto provide an oscillating signal that may be used to downconvert thesignal received from the antenna with one or more other signals. Theoscillator modules 422 and 436 may comprise any kind of oscillator withany different electrical properties. In one example, the oscillatormodule 422 provides an oscillating signal to the filter module 420. Theoscillator module 434 may provide an oscillating signal to the filtermodule 436.

The oscillating modules 422 and 436, either individually or together,may be local or remote. In one example, the oscillating module 422and/or the oscillating module 436 may be remotely located and configuredto provide an oscillating signal to one or more receiving radiofrequency units. In some embodiments, a single oscillating module mayprovide an oscillating signal to both the mixer module 418 and 432,respectively (e.g., optionally via a filter). In one example, the localoscillator signal from the oscillator module may be altered (e.g.,oscillation increased or decreased) and provided to a different part ofthe circuit.

Those skilled in the art will appreciate that each of the oscillatormodules 422 and 436 may be the same as each other. For example,oscillator modules 422 and 436 may both be oscillators sharing the sameelectrical properties or, alternately, the oscillator modules 422 and436 may be another kind of oscillator and/or with different electricalproperties.

Each oscillator modules 422 and 436 may include one or more components.For example, the oscillator module 422 may comprise one or moreoscillators.

The phase control module 414 may be configured to generate a phasecontrol signal to control the phase of a processed signal. In oneexample, the phase control module 414 receives the filtered signal fromthe amplifier/attenuator module 412 and mixes the amplified orattenuated signal with the filtered local oscillator or thedownconverted signal from the first downconverter (e.g., mixer module418, filter module 420, and oscillator module 422). The phase controlmodule 414 may filter and compare the filtered, mixed signal with apredetermined phase value to generate a phase control signal based onthe comparison. By mixing the oscillator signal with the sampled signalfrom the coupler prior to determining the phase of the signal, thefrequency of the signal is reduced and lower priced components may beused in the phase control module 414.

In some embodiments, the phase control module 418 uses a coupling portin the same path as RSL. The coupling port may sample the signal. Insome embodiments, the coupling port comprises a capacitive tap. In someembodiments, a preexisting transmitter may be modified to take advantageof one or more systems and methods described herein. In one example, themixer and filter of the phase control module 418 is a part of the RSLfunctionality. A splitter may be used to split the signal between theRSL and a phase comparator (discussed herein). The phase comparator maygenerate the phase control signal based on a comparison of the phase ofthe signal from the mixer and a predetermined phase value.

In various embodiments, the coupling port for both input amplitude andphase can be coupled before the Rx LNA (e.g., low noise amplifier 412),after LNA 412, or after the 1^(st) down-conversion (e.g., via the mixermodule 418, filter module 420, and the oscillator module 422), dependingon, for example, requirements of cost and accuracy.

The phase control module 414 may comprise a variety of differentcomponents (e.g., a mixer, filter, splitter, and a comparison module).The phase control module 418 is further described with regard to FIG. 8herein. In various embodiments, one phase control module 414 may receivesignals from a plurality of different receiving radio frequency unitsand provide phase control signals to one or more of the differentreceiving radio frequency units.

The automatic gain control modules 426, 440, and 442 may compriseautomatic gain control (AGC) circuits configured to increase or decreasethe gain of the signal received from the antenna 404 with one or moreother signals. The automatic gain control modules 426, 440, and 442 maycomprise many different types of AGCs with many different electricalproperties. In one example, the automatic gain control module 426increases or decreases the gain of the signal received from theamplifier/attenuator module 424. The automatic gain control module 426may adjust the gain of the signal based on a gain control signal.Similarly, the automatic gain control module 440 increases or decreasesthe gain of the signal received from the amplifier/attenuator module438. In some embodiments, the automatic gain control module 440 mayincrease or decrease the gain of the signal based on a gain controlsignal. The automatic gain control module 442 may also increase ordecrease the gain of the signal received from the automatic gain controlmodule 440 and/or generate the gain control signal. In some embodiments,the automatic gain control module 442 may compare the amplification ofthe signal from the automatic gain control module 440 to a predeterminedgain value and generate the gain control signal based on the comparison.The gain control signal may control the automatic gain control module426 and/or the automatic gain control module 440.

Those skilled in the art will appreciate that each of the automatic gaincontrol modules 426, 440, and 442 may be the same as one or more otherautomatic gain control modules. For example, automatic gain controlmodules 426 and 440 may both be AGCs sharing the same electricalproperties or, alternately, the automatic gain control modules 426 and440 may be another kind of AGC and/or with different electricalproperties.

Each automatic gain control modules 426, 440, and 442 may include one ormore components. For example, the automatic gain control module 426 maycomprise one or more AGCs.

The phase adjuster 428 may comprise a variable phase control circuitconfigured to increase or decrease the phase of the signal received fromthe antenna 404. The phase adjuster 428 may comprise any different typeof phase adjuster with different electrical properties. In one example,the phase adjuster 428 increases or decreases the phase of the signalreceived from the automatic gain control module 426. The phase adjuster428 may adjust the phase of the signal based on a phase control signalfrom the phase control module 414.

The phase adjuster 428 may include one or more components. For example,the phase adjuster 428 may comprise one or more phase control elements.

It will be appreciated that a “module” may comprise software, hardware,firmware, and/or circuitry. In one example one or more software programscomprising instructions capable of being executable by a processor mayperform one or more of the functions of the modules described herein. Inanother example, circuitry may perform the same or similar functions.Alternative embodiments may comprise more, less, or functionallyequivalent modules and still be within the scope of present embodiments.For example, as previously discussed, the functions of the variousmodules may be combined or divided differently.

FIG. 5 depicts a circuit diagram 500 illustrating an exemplary receivingradio frequency unit 502 with a phase control module 510 coupled to acoupler 508 near the diplexer 506 and a first downconverter module 512in some embodiments. The receiving radio frequency unit 502 may becoupled to an antenna 504. In some embodiments, the receiving radiofrequency unit 502 comprises components similar to receiving radiofrequency unit 402 described with regard to FIG. 4.

For example, the receiving radio frequency unit 502 may comprise adiplexer 506, coupler 508, a phase control module 510, a firstdownconverter module 512, an AGC module 514, a phase adjuster 516, asecond downconverter module 518, an AGC module 520, and an AGC module522. The receiving radio frequency unit 502 may also comprise additionalcomponents (e.g., as shown in FIG. 5 and discussed with regard to FIG.4).

A signal may be received by a diplexer 506 via the antenna 504. Acoupler 508 may provide the signal to the phase control module 510. Thephase control module 510 may function in a manner as similar phasecontrol module 414 described with regard to FIG. 4. In one example, thephase control module 510 may mix the signal from the coupler 508 withthe filtered oscillator signal of the oscillator module of the firstdownconverter module 512. The phase control module 510 may filter and/orcompare a phase of the mixed signal with a predetermined phase value tocreate a phase control signal which controls the phase adjuster 516.

The downconverter module 512 may downconvert the signal received fromthe diplexer 506. In some embodiments, the signal is filtered,attenuated or amplified (e.g., via a low noise amplifier) prior todownconversion. The downconverter module 512 may comprise an oscillatormodule that provides a signal to a filter and is subsequently mixed withthe signal received from the antenna 504 to downconvert the signal.

The signal may be filtered and the gain adjusted by the AGC module 514.The phase of the signal may be altered by the phase adjuster 516 basedon the phase control signal from the phase control module 510. Thesignal may then be filtered and downconverted by the second downconvertmodule 518. Like the downconvert module 512, the downconvert module 518may comprise an oscillator module that provides a signal to a filter andis subsequently mixed with the signal received from the antenna 504 todownconvert the signal. The output of the downconvert module 518 may bean output signal.

The AGC module 520 may adjust the gain of the signal after attenuatingor amplifying the signal from the downconverter module 518. The AGCmodule 514 and/or the AGC module 520 may adjust the gain of the filterbased on a gain control signal.

In some embodiments, the AGC module 522 may compare the gain of thesignal to a predetermined gain value and control the AGC module 514and/or the AGC module 520 to increase or decrease the gain of thesignal.

FIG. 6 depicts a circuit diagram illustrating an exemplary receivingradio frequency unit 602 with a phase control module 612 coupled to afirst downconverter module 608 and a second downconverter module 610 insome embodiments. The receiving radio frequency unit 602 may be coupledto an antenna 604 via the diplexer 606. In some embodiments, thereceiving radio frequency unit 602 comprises components similar toreceiving radio frequency unit 402 described with regard to FIG. 4.

For example, the receiving radio frequency unit 602 may comprise a firstdownconverter module 608, a second downconverter module 610, a phasecontrol module 612, an AGC module 614, an AGC module 616, a phaseadjuster 618, and an AGC module 620. Unlike the phase control module 502(discussed with regard to FIG. 5) which mixes a signal from a couplerwith the oscillator signal from the first downconverter module 512, thephase control module 612 mixes a filtered oscillator signal from thefirst downconverter module 608 with the a filtered oscillator signalfrom the second downconverter module 610. The phase control module 612filters the mixed signal, and compares the phase of the filtered mixedsignal with a predetermined phase value to generate the phase controlsignal. The phase control signal may control the phase adjuster 618 toadjust the phase of the signal.

The receiving radio frequency unit 602 may also comprise the AGC module620 which may be configured to compare the gain of the signal to apredetermined gain value to generate a gain control signal. The gaincontrol signal may control the AGC module 614 and/or the AGC module 616to increase or decrease the gain of the signal.

Those skilled in the art will appreciate that, like the receiving radiofrequency unit 402 discussed with regard to FIG. 4, the receiving radiofrequency unit 502 and the receiving radio frequency unit 602 maycomprise a waveguide and/or a waveguide filter. The waveguide and/orwaveguide filter may operate in a manner as discussed with regard toFIG. 4.

Further, those skilled in the art will appreciate that the receivingradio frequency units of FIGS. 4-6 may provide signals to a signalcombiner. The signal combiner may combine the signals of two or morereceiving radio frequency units.

FIG. 7 is a flow chart of an exemplary method for combining signals,with similar gain and phase, from different exemplary microwavereceiving radio frequency units. In step 702, an antenna 404 receives awireless signal and provides the signal to the receiving radio frequencyunit 402. In some embodiments, the electromagnetic wave energy of thewireless signal propagates through a waveguide coupled to the antenna404 and is subsequently filtered with a waveguide filter 408 in step 704before being provided to the receiving radio frequency unit 402 via thediplexer 410. In various embodiments, the waveguide 406, the waveguidefilter 408, and/or the diplexer 410 are optional.

In step 706, the first downconverter module (e.g., the mixer module 418,the filter module 420, and/or the oscillator module 422) downconvertsthe signal from the diplexer 410 (received via the low noise amplifier412). In some embodiments, the first downconverter module downconvertsthe signal to an intermediate frequency (IF) signal.

In step 708, the phase control module 414 mixes the signal from theantenna 404 (e.g., provided by the amplifier/attenuator module 412) withthe filtered oscillator signal (e.g., filtered by filter module 420 andthe oscillator module provided by the oscillator module 422) from thefirst downconverter module. The phase control module 414 then comparesthe phase of the mixed signal to a predetermined phase value in step710. In various embodiments, the predetermined phase value is set basedon the characteristics of one or more receivers and/or the signal to beadjusted.

In step 712, the phase adjuster 428 may adjust the phase of thedownconverted signal (e.g., received from the AGC module 426) based onthe comparison (e.g., based on a phase control signal from the phasecontrol module 414). In some embodiments, the phase of the signal may beadjusted at any point in the circuit of receiving radio frequency unit402.

In step 714, the AGC 442 compares the gain of the downconverted modulefrom the second downconverter (e.g., the mixer module 432, the filtermodule 434, and the oscillator module 436) with a predetermined gainvalue to create a gain control signal. The predetermined gain value maybe based on the characteristics of one or more receivers and/or thesignal to be adjusted.

In step 716, the AGC module 426 adjusts the signal from theamplifier/attenuator 424 based on the gain control signal from the AGC442. Those skilled in the art will appreciate that the gain of thesignal may be adjusted at any point in the circuit of receiving radiofrequency unit 402.

In step 718, steps 702-716 may be performed with a second receivingradio frequency unit. For example, a second receiving radio frequencyunit may have components very similar to the first receiving radiofrequency unit. The second receiving radio frequency unit may receivethe signal via an antenna, propagate the signal with a waveguide andfilter the signal with a waveguide filter. The second receiving radiofrequency unit may comprise a phase control module configured to mix thesignal from the antenna (e.g., received via a low noise amplifier 412)and a filtered, oscillator signal from the first downconverter module ofthe second receiving radio frequency unit. The mixed signal may befiltered and the phase of the filtered mixed signal may be compared tothe predetermined phase value to generate a phase control signal tocontrol the phase adjuster of the second receiving radio frequency unitto adjust the phase. Further, the second receiving radio frequency unitmay comprise an AGC module configured to compare the gain of the signalto a predetermined gain value to generate a gain control signal based onthe comparison. One or more AGC modules may adjust the gain based on thegain control signal.

In step 720, the phase and gain adjusted signal from the first receivingradio frequency unit may be combined with the phase and gain adjustedsignal from the second receiving radio frequency unit. The phase andgain of both signals may be the same or substantially similar.

FIG. 8 is a block diagram of a phase control module 802 in someembodiments. The phase control module 802 may comprise the mixer 804,the filter 806, the phase comparator 808, and the amplifier 810. Thephase control module 802 may be within a receiving radio frequency unitwhich also comprises an amplifier/attenuator module 812, a filter module814, a downconverter module (e.g., comprising a mixer module 816, afilter module 818, and an oscillator module 820), anamplifier/attenuator 822, a phase adjuster module 824, and a filtermodule 826.

In various embodiments, the mixer 804 mixes a signal from the antenna(e.g., via a diplexer, waveguide filter, waveguide, and/or an antenna)with a signal from a downconverter module. In one example, the signal isamplified with the amplifier/attenuator module 812, filtered with thefilter module 814, and downconverted (e.g., by mixing the signal fromthe filter module 814 with the filtered oscillator signal from theoscillator module 820 and the filter 818). The downconverted signal maybe an intermediate frequency signal. The mixer 804 of the phase controlmodule 802 may receive the filtered oscillator module from thedownconverter module as well as the signal from the antenna. In someembodiments, the mixer 804 may mix two filtered oscillator signals fromtwo downconverters or may mix an amplified or attenuated signal with theoscillator signals. Those skilled in the art will appreciate that themixer 804 may mix any two signals from any two or more points in thereceiving radio frequency unit. In some embodiments, the mixer 804 isoptional and the phase comparator may compare the phase of any signalfrom any point within the receiving radio frequency unit.

The filter module 806 filters the mixed signal from the mixer 804 andprovides the signal to the phase comparator 808. The phase comparator808 may be a chip, a processor, or a module configured to compare thephase of the signal from the filter 806 to a predetermined phase value.In one example, the phase comparator 808 may be an RF/IF detector. Thephase comparator 808 generates a phase control signal based on thecomparison and the filter 810 filters the phase control signal beforeproviding the phase control signal to the phase adjuster 824.

Based on the phase control signal, the phase adjuster 824 may adjust thedownconverted signal from the downconverter module via theamplifier/attenuator module 822. The phase adjusted signal issubsequently filtered by the filter module 826.

The predetermined phase value and/or the predetermined gain value may beset in any number of ways. In various embodiments, a user may set thepredetermined phase value and/or the predetermined gain value within achip. In one example, the predetermined phase value may be set withinthe phase comparator 808. In some embodiments, a pilot signal is sent toone or more receiving radio frequency units. The phase comparator 808may set the predetermined phase value and/or the predetermined gainvalue based on the pilot signal.

In various embodiments, one receiving radio frequency unit may receivethe predetermined phase value and/or the predetermined gain value fromanother receiving radio frequency unit. For example, a first receivingradio frequency unit may request the predetermined phase value and/orthe predetermined gain value from a digital device and/or anotherreceiving radio frequency unit. The digital device or receiving radiofrequency unit may provide the predetermined phase value and/or thepredetermined gain value to the requesting receiving radio frequencyunit. In some embodiments, an receiving radio frequency unit providesthe predetermined phase value and/or the predetermined gain value to oneor more other predetermined phase value (e.g., when the receiving radiofrequency unit changes, at predetermined intervals, or upon request by auser).

Those skilled in the art will appreciate that the gain of the signal maybe similarly adjusted. For example, the gain of the signal may becompared to a predetermined gain value to generate a gain controlsignal. An AGC may be controlled with the gain control signal toincrease or decrease the gain of the signal.

The gain and/or the phase of a signal may be adjusted at any pointwithin the receiving radio frequency unit. Further, the gain and/or thephase of the signal may be adjusted any number of time. In one example,the phase of the signal is adjusted multiple times based on the samephase control signal. In another example, the phase of the signal iscompared multiple times to one or more predetermined phase values andadjusted based on the comparison.

FIG. 9 is a flow chart of an exemplary method for controlling a phase ofa signal in an exemplary microwave receiving radio frequency unit. Instep 902, a signal is received by the receiving radio frequency unit. Instep 904, the signal is amplified by the amplifier/attenuator module 812and filtered by the filter module 814. In step 906, the downconvertermodule downconverts the signal to form an IF signal (e.g., using theoscillator module 820, the filter module 818, and the mixer module 816).

In step 908, the mixer 804 of the phase control module 802 mixes thesignal from the antenna (e.g., received via any number of componentsbetween the phase control module 802 and the antenna) with theoscillator signal from the downconverter module. In step 910, theoptional filter module 806 filters the mixed signal from the mixer 804.

In step 912, the phase comparator compares the phase of the mixed signalwith a predetermined phase value to create or generate the phase controlsignal. The phase control signal may be amplified or attenuated with theamplifier/attenuator module 810 in step 914.

In step 916, the phase control signal controls the phase adjuster 824which adjusts the phase of the signal received from theamplifier/attenuator module 822. As a result, the phase adjuster 824adjusts the phase of the signal based on the comparison of the phasecomparator 808.

Regarding FIGS. 10, 11, and 12, are directed to a receiving radiofrequency unit integrated with a demodulator and an analog-to-digitalconverter (ADC). Each receiving radio frequency unit may receive thesignal from the wireless communication source, propagate theelectromagnetic wave energy through a waveguide, and filter theelectromagnetic wave energy with a waveguide filter prior to passing thesignal through the diplexer. These different architectures may keephitless protection and regular AGC features.

FIG. 10 is an exemplary receiving radio frequency unit 1002 with ademodulator 1032 and an ADC module 1026 in some embodiments. Thereceiving radio frequency unit 1002 may be coupled to an antenna 1004.In some embodiments, the receiving radio frequency unit 1002 comprisescomponents similar to receiving radio frequency unit 402 described withregard to FIG. 4.

For example, the receiving radio frequency unit 1002 may comprise adiplexer 1006, coupler 1008, a phase control module 1010, a firstdownconverter module 1012, an AGC module 1014, a phase adjuster 1016, asecond downconverter module 1018, an AGC module 1020, a postdistortionmodule 1022, an ADC 1024, an ADC module 1026, a filter module 1028, anAGC module 1030, and a demodulator 1032.

As described regarding FIG. 5, a signal may be received by a diplexer1006 via the antenna 1004. A coupler 1008 may provide the signal to thephase control module 1010. The phase control module 1010 may function ina manner as similar phase control module 414 described with regard toFIG. 4 and phase control module 800 described with regard to FIG. 8. Inone example, the phase control module 1010 may mix the signal from thecoupler 1008 with the oscillator signal from the first downconvertermodule 1012 (e.g., from the oscillator of the first downconverter module1012). The phase control module 1010 may filter and/or compare a phaseof the mixed signal with a predetermined phase value to create a phasecontrol signal which controls the phase adjuster 1016.

The downconverter module 1012 may downconvert the signal received fromthe diplexer 1006. In some embodiments, the signal is filtered,attenuated or amplified prior to downconversion. The downconvertermodule 1012 may comprise an oscillator module that provides anoscillating signal to a filter and is subsequently mixed with thereceived signal from the antenna 1004 to downconvert the signal.

The signal may be filtered and the gain adjusted by the AGC module 1014.The phase of the signal may be altered by the phase adjuster 1016 basedon the phase control signal from the phase control module 1010. Thesignal may then be filtered and downconverted by the seconddownconverter module 1018. Like the downconverter module 1012, thedownconvert module 1018 may comprise an oscillator module that providesan oscillating signal to a filter and is subsequently mixed with thesignal received from the antenna 1004 to downconvert the signal.

The AGC module 1020 may adjust the gain of the signal after attenuatingor amplifying the signal from the downconverter module 1018. The AGCmodule 1020 may adjust the gain of the filter based on a gain controlsignal.

The postdistortion module 1022 may receive the signal from the AGCmodule 1020 and improve the linearity of the signal. In variousembodiments, the postdistortion module 1022 inversely models theamplifier's gain and phase characteristics and produces a signal that ismore linear and reduces distortion. In one example, “inverse distortion”is introduced to cancel non-linearity. The postdistortion module 1022may receive a postdistortion control signal from the phase controlmodule 1010 via the ADC (analog to digital converter) module 1024. Inthe receiver application, pre-distortion before the ADC module 1026 mayhelp the overall linearity when receiver with high RSL. The adaptivepre-distortion may assist the free spurious dynamic range for the ADC,and further minimizes quantization error due to any nonlinearity causedin the receiver chain.

The demodulator module 1032 may receive the signal from thepostdistortion module 1022 via the ADC module 1026 and the filter module1028. The demodulator module 1032 may provide the in-phase (I) andquadrature (Q) signals. The AGC module 1030 may compare the gain of thesignal to a predetermined gain value and control the AGC module 1014and/or the AGC module 1020 to increase or decrease the gain of thesignal.

FIG. 11 is another exemplary receiving radio frequency unit 1102 with ademodulator and a postdistortion module in some embodiments. Thereceiving radio frequency unit 1102 may be coupled to an antenna 1104.

Block diagram 1100 comprises an antenna 1104 and a diplexer 1110 coupledto the waveguide 1106. The waveguide 1106 may provide the signal fromthe antenna 1104 to the diplexer 1110 via a waveguide filter 1108. Thediplexer 1110 may provide the signal to the receiving radio frequencyunit 1102. In some embodiments, the receiving radio frequency unit 1102may comprise the waveguide 1106, the waveguide filter 1108, and/or thediplexer 1110.

In some embodiments, the receiving radio frequency unit 1102 comprisescomponents similar to receiving radio frequency unit 402 described withregard to FIG. 4 and receiving radio frequency unit 1002 described withregard to FIG. 10. The receiving radio frequency unit 1102 may comprisean amplifier/attenuator module 1112, a phase control module 1114, afirst downconverter module 1116, a phase adjuster 1120, an AGC module1118 and an AGC module 1124. Those skilled in the art will appreciatethat the receiving radio frequency unit 1102 may comprise othercomponents similar to receiving radio frequency unit 1002 as describedwith regard to FIG. 10.

Unlike the phase control module 1010 which mixes a signal from a couplerwith the downconverted signal from the first downconverter module 1012,the phase control module 1114 receives the signal amplified and/orattenuated by the amplification/attenuator module 1112. The phasecontrol module 1114 may mix the signal from the amplification/attenuatormodule 1112 with the oscillator signal from the downconverter module1116, filters the mixed signal, and compares the filtered mixed signalwith a predetermined phase value to generate a phase control signal. Thephase control signal may control the phase adjuster 1120 to adjust thephase of the signal received by the antenna 1104. The receiving radiofrequency unit 1102 may also comprise the AGC module 1124 configured tocompare the gain of the signal to a predetermined gain value to generatea gain control signal. The gain control signal may control the AGCmodule 1116 and/or any other AGC module to increase or decrease the gainof the signal.

FIG. 12 is a further exemplary receiving radio frequency unit 1202 witha demodulator and a postdistortion module in some embodiments. Thereceiving radio frequency unit 1202 may be coupled to an antenna 1204.In some embodiments, the receiving radio frequency unit 1202 comprisescomponents similar to receiving radio frequency unit 402 described withregard to FIG. 4 and receiving radio frequency unit 1002 described withregard to FIG. 10.

The receiving radio frequency unit 1202 may comprise a diplexer 1206, afirst downconverter module 1208, a second downconverter module 1212, aphase control module 1210, an AGC module 1216, a phase adjuster 1218,and an AGC module 1214. Those skilled in the art will appreciate thatthe receiving radio frequency unit 1202 may comprise other componentssimilar to receiving radio frequency unit 1002 as described with regardto FIG. 10.

Unlike the phase control module 1010 which mixes a signal from a couplerwith the downconverted signal from the first downconverter module 1012,the phase control module 1210 may mix a downconverted signal from thefirst downconverter module 1208 with the oscillator signal from thesecond downconverter module 1212. The phase control module 1210 filtersthe mixed signal, and compares the filtered mixed signal with apredetermined phase value to generate a phase control signal. The phasecontrol signal may control the phase adjuster 1218 to adjust the phaseof the signal received from the antenna 1204. The receiving radiofrequency unit 1202 may also comprise the AGC module 1214 configured tocompare the gain of the signal to a predetermined gain value to generatea gain control signal. The gain control signal may control the AGCmodule 1216 or any other AGC module to increase or decrease the gain ofthe signal.

Those skilled in the art will appreciate that, like the receiving radiofrequency unit 1102 discussed with regard to FIG. 11, the receivingradio frequency unit 1002 and the receiving radio frequency unit 1202may comprise a waveguide and/or a waveguide filter. The waveguide and/orwaveguide filter may operate in a manner as discussed with regard toFIG. 11.

Further, those skilled in the art will appreciate that the receivingradio frequency units of FIGS. 10-12 may provide signals to a signalcombiner. The signal combiner may combine the signals of two or morereceiving radio frequency units. In some embodiments, the signalcombiner combines the inphase (I) signal from two or more receivingradio frequency units and combines the quadrature (Q) signal from two ormore receiving radio frequency units.

The above-described functions and components can be comprised ofinstructions that are stored on a storage medium such as a computerreadable medium. The instructions can be retrieved and executed by aprocessor. Some examples of instructions are software, program code, andfirmware. Some examples of storage medium are memory devices, tape,disks, integrated circuits, and servers. The instructions areoperational when executed by the processor to direct the processor tooperate in accord with some embodiments. Those skilled in the art arefamiliar with instructions, processor(s), and storage medium.

Various embodiments are described herein as examples. It will beapparent to those skilled in the art that various modifications may bemade and other embodiments can be used without departing from thebroader scope of the present invention. Therefore, these and othervariations upon the exemplary embodiments are intended to be covered bythe present invention(s).

The invention claimed is:
 1. A system, comprising: a first receivingradio frequency unit comprising: a first downconverter configured todownconvert a received signal from a first antenna to an intermediatefrequency to create an intermediate frequency signal; a phase comparatorconfigured to mix the received signal and an oscillating signal from thefirst downconverter to create a mixed signal, compare a phase of themixed signal to a predetermined phase, and generate a phase controlsignal based on the comparison; a phase adjuster configured to alter thephase of the intermediate frequency signal based on the phase controlsignal from the phase comparator; a second downconverter configured todownconvert the phase-shifted intermediate frequency signal to create anoutput signal; and a waveguide configured to receive the received signalfrom the first antenna and provide the received signal to the firstdownconverter.
 2. The system of claim 1, wherein the downconvertedsignal comprises the intermediate frequency signal.
 3. The system ofclaim 1, wherein the received signal is received from a diplexer whichis coupled to the first antenna.
 4. The system of claim 3, wherein thereceived signal is filtered with a low noise amplifier after beingprovided from the diplexer.
 5. The system of claim 1, wherein the firstdownconverter is configured to mix a filtered oscillator signal with thereceived signal to create the intermediate frequency signal.
 6. Thesystem of claim 1, further comprising comparing a gain of thedownconverted phase-shifted intermediate frequency signal to apredetermined gain value and adjusting the gain of the downconvertedphase-shifted intermediate frequency signal based on the comparison. 7.The system of claim 1, further comprising a second receiving radiofrequency unit configured to receive a received signal from a secondantenna, the second received radio frequency unit configured to alter aphase of the received signal from the second antenna to a phase that issubstantially similar to the altered phase of the intermediate frequencysignal of the first received radio frequency unit.
 8. The system ofclaim 7, wherein the second receiving radio frequency unit is configuredto adjust a gain of an output signal, a gain of an output signal fromthe second receiving radio frequency unit being substantially similar toa gain of the output signal from the first receiving radio frequencyunit.
 9. The system of claim 7, further comprising a signal combinerconfigured to combine the output signal from the first receiving radiofrequency unit and an output signal from the second receiving radiofrequency unit.
 10. The system of claim 7, further comprising: apostdistortion module configured to add distortion to the output signal;and a demodulator configured to receive the output signal from thepostdistortion module and provide in-phase (I) and quadrature (Q)signals.
 11. The system of claim 1, wherein the first antenna is part ofa point-to-point microwave communication system.
 12. A systemcomprising: a first receiving radio frequency unit configured to comparea phase of a received signal from a first antenna to a predeterminedphase value, and to adjust the phase of the received signal from thefirst antenna to generate a first phase-adjusted signal; a secondreceiving radio frequency unit configured to compare a phase of areceived signal from a second antenna to the predetermined phase value,and to adjust the phase of the received signal from the second antennato generate a second phase-adjusted signal; and a signal combinerconfigured to combine the first and second phase-adjusted signals, thephase of the first and second phase-adjusted signals being substantiallysimilar; wherein the first and second receiving radio frequency unitsfurther comprise a first and second waveguide, respectively, the firstand second waveguides configured to receive the received signal from thefirst and second antenna, respectively, prior to comparison of thereceived signals to the predetermined phase value.
 13. The system ofclaim 12, wherein the first receiving radio frequency unit is configuredto downconvert the received signal from the first antenna to generate afirst downconverted signal and the second receiving radio frequency unitis configured to downconvert the received signal from the second antennato generate a second downconverted signal.
 14. The system of claim 13,wherein the first receiving radio frequency unit configured to compare aphase of the received signal from the first antenna comprises the firstreceiving radio frequency unit configured to mix the received signalwith an oscillator signal from the first downconverter and to comparethe phase of the mixed signal to the predetermined phase value.
 15. Thesystem of claim 14, wherein the first receiving radio frequency unitconfigured to adjust the phase of the received signal from the firstantenna comprises the first receiving radio frequency unit configured toadjust the phase of the first downconverted signal based on thecomparison.
 16. The system of claim 14, wherein the first downconvertedsignal comprises an intermediate frequency signal.
 17. The system ofclaim 14, wherein the first receiving radio frequency unit is furtherconfigured to downconvert the first phase-adjusted downconverted signalto generate a first output signal.
 18. The system of claim 17, whereinthe second receiving radio frequency unit configured to compare a phaseof the received signal from the second antenna comprises the secondreceiving radio frequency unit configured to mix the received signalwith the second downconverted signal and to compare the phase of themixed signal to the predetermined phase value.
 19. The system of claim18, wherein the second receiving radio frequency unit configured toadjust the phase of the received signal from the second antennacomprises the second receiving radio frequency unit configured to adjustthe phase of the second downconverted signal based on the comparison.20. The system of claim 19, wherein the second receiving radio frequencyunit is further configured to downconvert the second phase-adjusteddownconverted signal to generate a second output signal.
 21. The systemof claim 20, wherein the signal combiner configured to combine the firstand second phase-adjusted signals comprises the signal combinerconfigured to combine the first and second output signals.
 22. Thesystem of claim 12, wherein the first and second antenna are part of apoint-to-point microwave communication system.
 23. A method comprising:comparing, by a first receiving radio frequency unit, a phase of areceived signal from a first antenna to a predetermined phase value;adjusting, by the first receiving radio frequency unit, the phase of thereceived signal from the first antenna to generate a firstphase-adjusted signal; comparing, by a second receiving radio frequencyunit, a phase of a received signal from a second antenna to thepredetermined phase value; adjusting, by the second receiving radiofrequency unit, the phase of the received signal from the second antennato generate a second phase-adjusted signal; combining the first andsecond phase-adjusted signals, the phase of the first and secondphase-adjusted signals being substantially similar; propagating thereceived signal from the first antenna through a first waveguide;filtering the received signal from the first antenna with a firstwaveguide filter prior to comparing the phase of the received signalfrom the first antenna to the predetermined phase value; propagating thereceived signal from the second antenna through a second waveguide; andfiltering the received signal from the second antenna with a secondwaveguide filter prior to comparing the phase of the received signalfrom the second antenna to the predetermined phase value.
 24. The methodof claim 23, further comprising downconverting, by the first receivingradio frequency unit, the received signal from the first antenna togenerate a first downconverted signal and downconverting, by the secondreceiving radio frequency unit, the received signal from the secondantenna to generate a second downconverted signal.
 25. The method ofclaim 24, wherein comparing, by the first receiving radio frequencyunit, the phase of the received signal from the first antenna, comprisesmixing, by the first receiving radio frequency unit, the received signalwith an oscillator signal, the oscillator signal also being mixed withthe received signal to provide the first downconverted signal, andcomparing, by the first receiving radio frequency unit, the phase of themixed signal to the predetermined phase value.
 26. The method of claim25, wherein adjusting, by the first receiving radio frequency unit, thephase of the received signal from the first antenna comprises adjusting,by the first receiving radio frequency unit, the phase of the firstdownconverted signal based on the comparison.
 27. The method of claim25, further comprising downconverting, by the first receiving radiofrequency unit, the first phase-adjusted downconverted signal togenerate a first output signal.
 28. The method of claim 27, whereincomparing, by the second receiving radio frequency unit, the phase ofthe received signal from the second antenna comprises mixing, by thesecond receiving radio frequency unit, the received signal with anoscillator signal and comparing the phase of the mixed signal to thepredetermined phase value.
 29. The method of claim 27, whereinadjusting, by the second receiving radio frequency unit, the phase ofthe received signal from the second antenna comprises adjusting thephase of the second downconverted signal based on the comparison. 30.The method of claim 28, further comprising downconverting, by the secondreceiving radio frequency unit, the second phase-adjusted downconvertedsignal to generate a second output signal.
 31. The method of claim 29,wherein combining the first and second phase-adjusted signals comprisescombining the first and second output signals.
 32. A system, comprising:a first receiving radio frequency unit comprising: a first downconverterconfigured to downconvert a received signal from a first antenna to anintermediate frequency to create an intermediate frequency signal; aphase comparator configured to mix the received signal and anoscillating signal from the first downconverter to create a mixedsignal, compare a phase of the mixed signal to a predetermined phase,and generate a phase control signal based on the comparison; a phaseadjuster configured to alter the phase of the intermediate frequencysignal based on the phase control signal from the phase comparator; anda second downconverter configured to downconvert the phase-shiftedintermediate frequency signal to create an output signal; wherein thereceived signal is received from a diplexer which is coupled to thefirst antenna.
 33. The system of claim 32, wherein the downconvertedsignal comprises the intermediate frequency signal.
 34. The system ofclaim 32, wherein the received signal is filtered with a low noiseamplifier after being provided from the diplexer.
 35. The system ofclaim 32, wherein the first downconverter is configured to mix afiltered oscillator signal with the received signal to create theintermediate frequency signal.
 36. The system of claim 32, furthercomprising comparing a gain of the downconverted phase-shiftedintermediate frequency signal to a predetermined gain value andadjusting the gain of the downconverted phase-shifted intermediatefrequency signal based on the comparison.
 37. A system, comprising: afirst receiving radio frequency unit comprising: a first downconverterconfigured to downconvert a received signal from a first antenna to anintermediate frequency to create an intermediate frequency signal; aphase comparator configured to mix the received signal and anoscillating signal from the first downconverter to create a mixedsignal, compare a phase of the mixed signal to a predetermined phase,and generate a phase control signal based on the comparison; a phaseadjuster configured to alter the phase of the intermediate frequencysignal based on the phase control signal from the phase comparator; asecond downconverter configured to downconvert the phase-shiftedintermediate frequency signal to create an output signal; and a secondreceiving radio frequency unit configured to receive a signal from asecond antenna, the second receiving radio frequency unit configured toalter a phase of the received signal from the second antenna to a phasethat is substantially similar to the altered phase of the intermediatefrequency signal of the first receiving radio frequency unit.
 38. Thesystem of claim 37, wherein the downconverted signal comprises theintermediate frequency signal.
 39. The system of claim 37, wherein thereceived signal from the first antenna is received from a diplexer whichis coupled to the first antenna.
 40. The system of claim 39, wherein thereceived signal from the first antenna is filtered with a low noiseamplifier after being provided from the diplexer.
 41. The system ofclaim 37, wherein the first downconverter is configured to mix afiltered oscillator signal with the received signal from the firstantenna to create the intermediate frequency signal.
 42. The system ofclaim 37, further comprising comparing a gain of the downconvertedphase-shifted intermediate frequency signal to a predetermined gainvalue and adjusting the gain of the downconverted phase-shiftedintermediate frequency signal based on the comparison.
 43. The system ofclaim 37, wherein the second receiving radio frequency unit isconfigured to adjust a gain of an output signal, a gain of an outputsignal from the second receiving radio frequency unit beingsubstantially similar to a gain of the output signal from the firstreceiving radio frequency unit.
 44. The system of claim 37, furthercomprising a signal combiner configured to combine the output signalfrom the first receiving radio frequency unit and an output signal fromthe second receiving radio frequency unit.
 45. The system of claim 37,further comprising: a postdistortion module configured to add distortionto the output signal; and a demodulator configured to receive the outputsignal from the postdistortion module and provide in-phase (I) andquadrature (Q) signals.
 46. A system comprising: a first receiving radiofrequency unit configured to compare a phase of a received signal from afirst antenna to a predetermined phase value, and to adjust the phase ofthe received signal from the first antenna to generate a firstphase-adjusted signal; a second receiving radio frequency unitconfigured to compare a phase of a received signal from a second antennato the predetermined phase value, and to adjust the phase of thereceived signal from the second antenna to generate a secondphase-adjusted signal; and a signal combiner configured to combine thefirst and second phase-adjusted signals, the phase of the first andsecond phase-adjusted signals being substantially similar; wherein thefirst receiving radio frequency unit is configured to downconvert thereceived signal from the first antenna to generate a first downconvertedsignal and the second receiving radio frequency unit is configured todownconvert the received signal from the second antenna to generate asecond downconverted signal.
 47. The system of claim 46, wherein thefirst receiving radio frequency unit configured to compare a phase ofthe received signal from the first antenna comprises the first receivingradio frequency unit configured to mix the received signal with anoscillator signal from the first downconverter and to compare the phaseof the mixed signal to the predetermined phase value.
 48. The system ofclaim 47, wherein the first receiving radio frequency unit configured toadjust the phase of the received signal from the first antenna comprisesthe first receiving radio frequency unit configured to adjust the phaseof the first downconverted signal based on the comparison.
 49. Thesystem of claim 47, wherein the first downconverted signal comprises anintermediate frequency signal.
 50. The system of claim 47, wherein thefirst receiving radio frequency unit is further configured todownconvert the first phase-adjusted downconverted signal to generate afirst output signal.
 51. The system of claim 50, wherein the secondreceiving radio frequency unit configured to compare a phase of thereceived signal from the second antenna comprises the second receivingradio frequency unit configured to mix the received signal with thesecond downconverted signal and to compare the phase of the mixed signalto the predetermined phase value.
 52. The system of claim 51, whereinthe second receiving radio frequency unit configured to adjust the phaseof the received signal from the second antenna comprises the secondreceiving radio frequency unit configured to adjust the phase of thesecond downconverted signal based on the comparison.
 53. The system ofclaim 52, wherein the second receiving radio frequency unit is furtherconfigured to downconvert the second phase-adjusted downconverted signalto generate a second output signal.
 54. The system of claim 53, whereinthe signal combiner configured to combine the first and secondphase-adjusted signals comprises the signal combiner configured tocombine the first and second output signals.
 55. A method comprising:comparing, by a first receiving radio frequency unit, a phase of areceived signal from a first antenna to a predetermined phase value;adjusting, by the first receiving radio frequency unit, the phase of thereceived signal from the first antenna to generate a firstphase-adjusted signal; comparing, by a second receiving radio frequencyunit, a phase of a received signal from a second antenna to thepredetermined phase value; adjusting, by the second receiving radiofrequency unit, the phase of the received signal from the second antennato generate a second phase-adjusted signal; combining the first andsecond phase-adjusted signals, the phase of the first and secondphase-adjusted signals being substantially similar; and downconverting,by the first receiving radio frequency unit, the received signal fromthe first antenna to generate a first downconverted signal anddownconverting, by the second receiving radio frequency unit, thereceived signal from the second antenna to generate a seconddownconverted signal.
 56. The method of claim 55, wherein comparing, bythe first receiving radio frequency unit, the phase of the receivedsignal from the first antenna, comprises mixing, by the first receivingradio frequency unit, the received signal with an oscillator signal, theoscillator signal also being mixed with the received signal to providethe first downconverted signal, and comparing, by the first receivingradio frequency unit, the phase of the mixed signal to the predeterminedphase value.
 57. The method of claim 56, wherein adjusting, by the firstreceiving radio frequency unit, the phase of the received signal fromthe first antenna comprises adjusting, by the first receiving radiofrequency unit, the phase of the first downconverted signal based on thecomparison.
 58. The method of claim 56, further comprisingdownconverting, by the first receiving radio frequency unit, the firstphase-adjusted downconverted signal to generate a first output signal.59. The method of claim 58, wherein comparing, by the second receivingradio frequency unit, the phase of the received signal from the secondantenna comprises mixing, by the second receiving radio frequency unit,the received signal with an oscillator signal and comparing the phase ofthe mixed signal to the predetermined phase value.
 60. The method ofclaim 58, wherein adjusting, by the second receiving radio frequencyunit, the phase of the received signal from the second antenna comprisesadjusting the phase of the second downconverted signal based on thecomparison.
 61. The method of claim 59, further comprisingdownconverting, by the second receiving radio frequency unit, the secondphase-adjusted downconverted signal to generate a second output signal.62. The method of claim 60, wherein combining the first and secondphase-adjusted signals comprises combining the first and second outputsignals.